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This review provides constructive and extensive information about the botanical characterization, distribution, traditional uses, phytochemistry and pharmacology of the genus Elegia. The genus Elegia L. is the second largest of the Restionaceae family, comprising 52 species, which are mainly used as materials for thatching. A comprehensive search of previously published literature was performed for studies on this genus, using databases with different key search words. This survey documented 52 Elegia species summarizing their previous taxonomic classification. In addition, 14 species were found to be studied for their phytochemical profile, revealing 14 chemical compounds. Concerning their biological activities, only one species (E. tectorum (L.f.) Moline and H.P.Linder) is reported for its anti-wrinkle activity. Moreover, two species are locally used for thatching and as materials for brooms. The present review highlights the Elegia genus as an important source of bioactive phytochemicals with flavonol glycosides being the main metabolites and reveals the uncharted territory of this genus for new research studies.
The plants of the Restionaceae family are found all over the southern hemisphere with approximately 360 species in Africa, 150 in Australia, 4 in New Zealand, 1 in Southwest Asia and 1 in South America. All the species of the genus Elegia are endemic to the Western and Eastern Cape Province of South Africa [1][3]. The genus Elegia L. is the second largest of the family with 52 species (Table 1) [5][7].
Table 1. All species of the genus Elegia L. and their previous botanical names.
Botanical Name |
Synonyms (Previous Botanical Name) |
E. acockii (Pillans) Moline and H.P.Linder |
Chondropetalum acockii Pillans |
E. aggregata (Mast.) Moline and H.P.Linder |
C. aggregatum (Mast) Pillans Dovea aggregata Mast. |
E. altigena Pillans |
- |
E. amoena Pillans |
- |
E. asperiflora (Nees) Kunth |
E. ciliata Mast. E. glauca Mast. E. lacerata Pillans Restio asperiflorus Nees |
E. atratiflora Esterh. |
- |
E. caespitosa Esterh. |
- |
E. capensis (Burm.f.) Schelpe |
E. verticillaris (L.f.) Kunth Equisetum capense Burm. f. Restio verticillaris L.f. |
E. coleura Nees ex Mast. |
E. exilis Mast. |
E. cuspidata Mast. |
- |
E. decipiens (Esterhuysen) Moline and H.P.Linder |
Chondropetalum decipiens Esterhuysen |
E. deustum (Rottb.) Kunth |
Chondropetalum deustum Rottb. Elegia deusta (Rottb.) Kunth Restio chondropetalum Nees |
E. dregeana Kunth |
- |
E. ebracteata (Kunth) Moline and H.P.Linder |
Chondropetalum ebracteatum (Kunth) Pillans Dovea ebracteata Kunth |
E. elephantina H.P.Linder |
- |
E. equisetacea Mast. |
E. equisetacea (Mast.) Mast. E. propinqua (Nees) Kunth var. equisetacea Mast |
E. esterhuyseniae Pillans |
- |
E. extensa Pillans |
- |
E. fastigiata Mast. |
- |
E. fenestrata Pillans |
- |
E. filacea Mast. |
E. gracilis N.E.Br. E. parviflora Pillans E. parviflora (Thunb.) Kunth E. parviflora Pillans var. filacea (Mast.) Pillans E. rehmanni Mast |
E. fistulosa Kunth |
- |
E. fucata Esterhuysen |
- |
E. galpinii N.E.Br. |
- |
E. grandis (Nees) Kunth |
Lamprocaulis grandis (Nees) Mast. Restio grandis Spreng. Ex Nees |
E. grandispicata H.P.Linder |
- |
E. hookeriana (Mast.) Moline and H.P.Linder |
Chondropetalum hookerianum (Mast.) Pillans Dovea bolusii Mast. D. hookeriana Mast. |
E. hutchinsonii Pillans |
- |
E. intermedia (Steud.) Pillans |
E. membranacea (Nees) Kunth. E. membranaceus Nees Restio intermedius Steud. R. membranaceus Nees |
E. juncea L. |
E. junacea L. E. propinqua (Nees) Kunth Elegia juncea L. var. geniculate Pillans Elegia propinqua (Nees) Kunth var. minor Mast. Restio elegia Murray Restio junceus (L.) Nees R. propinquus Nees |
E. macrocarpa (Kunth) Moline and H.P.Linder |
Chondropetalum macrocarpum (Kunth) Kunth Dovea macrocarpa Kunth |
E. marlothii (Pillans) Moline and H.P.Linder |
Chondropetalum marlothii (Pillans) Pillans Dovea marlothii Pillans |
E. microcarpa (Kunth) Moline and H.P.Linder |
Chondropetalum microcarpum (Kunth) Pillans Dovea rigens Mast. D. microcarpa Kunth |
E. mucronata (Nees) Kunth |
Chondropetalum mucronatum (Nees) Pillans Dovea mucronata (Nees) Mast. E. panicoides Kunth Restio mucronatus Nees |
E. muirii Pillans |
- |
E. namaquense H.P.Linder and Helme |
- |
E. neesii Mast. |
Lamprocaulis neesii (Mast.) Mast. L. schlechteri Gilg-Ben. |
E. nuda (Rottb.) Kunth |
Chondropetalum nudum Rottb. Cuculifera dura Nees Dovea nuda (Rottb.) Pillans E. elongata Mast. Restio acuminatus Thunb. R. nudus (Rottb.) Nees |
E. persistens Mast. |
- |
E. prominens Pillans |
- |
E. racemosa (Poir.) Pers. |
Dovea racemosa (Poir.) Mast. E. bella Pillans E. fusca N.E. Br. E. racemosa (Poir.) Pers. Restio racemosa Poir. |
E. recta (Mast.) Moline and H.P.Linder |
Chondropetalum rectum (Mast.) Pillans Dovea recta Mast.
|
E. rigida Mast. |
E. obtusiflora Mast. E. parviflora Pillans var. rigida (Mast.) E. spathacea Mast. var. attenuata Pillans |
E. spathacea Mast. |
- |
E. squamosa Mast. |
E. pectinata Pillans |
E. stipularis Mast. |
- |
E. stokoei Pillans |
- |
E. tectorum (L.f.) Moline and H.P.Linder |
Chondropetalum tectorum (L.f) Raf. Dovea cylindrostachya Mast. D. tectorum (L.f.) Mast. E. tectorumi (Mast.) Moline and H.P. Linder Restio tectorum L.f. |
E. thyrsifera (Rotth.) Pers. |
E. acuminata Mast. Restio thyrsifer Rottb. |
E. thyrsoidea (Mast.) Pillans |
Dovea thyrsoidea Mast. |
E. vaginulata Mast. |
- |
E. verreauxii Mast. |
- |
Plants of the Restionaceae family are evergreen, grass-like plants, caespitose, rhizomatous or stoloniferous, growing to a maximum height of 3.5 m (depending on the species) [1][3]. Species belonging to the Elegia L. are either caespitose or rhizomatous [3]. The stems of the restios are called culms and they are the only green part of the plant and are, therefore, considered as the main photosynthetic organ [1][3]. Τhe culms of the Elegia species could be simple or branched. The leaves of the restios are reduced to sheaths in adult plants, they can also be persistent, but usually the plants lose these sheaths. Male and female inflorescences are usually similar, much branched with numerous small, often dark-coloured spikelets or solitary flowers [1][3]. Spikelets consist of flowers and large bracts (a modified leaf) that are called spathes. Spathes are prominent and often obscure the flowers [1]. Restios’ flowers have three petals and three sepals forming a perianth of six tepals whose color, shape, size and texture vary for each species [1]. Each flower is minute (<10 mm long) and is situated on a central axis above a bract. The fruit can be either a 1–3 locular capsule or a 1-locular nut [1][3]. The seeds have an elliptical shape and are between 1–2 mm long [1].
The entire family is wind-pollinated and all genera apart from Coleocarya S.T. Blake and Lepyrodia R. Br. are dioecious. The enlarged bracts and spathes of the Elegia genus appear to work as air scoops, that guide the wind to pass through the styles. Alternatively, they are able to cause local eddies that help the pollen drop down onto the styles. These mechanisms have a high efficacy, since very little pollen of other species has been detected on the styles of the Elegia species [1].
Species |
Compounds |
Plant Part |
References |
E. capensis (Burm. F.) Schelpe |
Myricetin 3-galactoside (5) Myricetin 3-arabinoside (6) Myricetin 3-rhamnoside (7) Quercetin 3-galactoside (4) Procyanidin * |
stem, inflorescences |
[11] |
E. cuspidata Mast. |
Syringetin 3-galactoside (12) Procyanidin * |
stem, inflorescences |
[11] |
E. deustum (Rottb.) Kunth |
Myricetin 3-galactoside (5) Myricetin 3-rhamnoside (6) Laricitrin 3-galactoside (9) Laricitrin 3-rhamnoside (10) Syringetin 3-galactoside (12) Syringetin 3-rhamnoside (14) Procyanidin * Prodelphinidin * |
aerial culm # |
[12] |
E. filacea Mast.
|
Laricitrin 3-galactoside (9) Syringetin 3-galactoside (12) Procyanidin * Sulphated flavonoids * |
stem, inflorescences |
[11] |
E. galpinii N.E.Br. |
Myricetin 3-galactoside (5) Laricitrin 3-galactoside (9) Laricitrin 3-diglycoside * Syringetin 3-galactoside (12) Procyanidin * |
stem, inflorescences |
[11] |
E. hookeriana (Mast.) Moline and H.P.Linder |
Myricetin 3-galactoside (5) Myricetin 3-rhamnoside (7) Laricitrin 3-galactoside (9) Laricitrin 3-rhamnoside (10) Syringetin 3-galactoside (12) Syringetin 3-arabinoside (13) Cyanidin 3-glycoside (anthocyanin) * |
stem, inflorescences; aerial culm # |
|
E. macrocarpa (Kunth) Moline and H.P.Linder |
Kaempferol (1) Quercetin (2)
|
aerial culm # |
[12] |
E. microcarpa (Kunth.) Moline and H.P.Linder |
Myricetin 3-galactoside (5) Laricitrin 3-galactoside (9) Laricitrin 3-rhamnoside (10) Syringetin 3-galactoside (12) Syringetin 3-arabinoside (13) Procyanidin * Prodelphinidin * |
aerial culm # |
[12] |
E. mucronata (Nees) Kunth |
Myricetin 3-galactoside (5) Procyanidin * Prodelphinidin * |
stem, inflorescences; aerial culm # |
|
E. nuda (Rottb.) Kunth |
Myricetin 3-galactoside (5) Myricetin 3-rhamnoside (7) Laricitrin 3-galactoside (9) Laricitrin 3-rhamnoside (10) Syringetin 3-galactoside (12) Procyanidin * Prodelphinidin * |
aerial culm # |
[12] |
E. persistens Mast. |
Myricetin 3-galactoside (5) Laricitrin 3-galactoside (9) Laricitrin 3-diglycoside * Syringetin 3-galactoside (12) Procyanidin * |
stem, inflorescences |
[11] |
E. recta (Mast.) Moline and H.P.Linder |
Myricetin 3-galactoside (5) Myricetin 3-rhamnoside (7) Laricitrin 3-galactoside (9) Laricitrin 3-rhamnoside (10) Syringetin 3-galactoside (12) Syringetin 3-arabinoside (13) Procyanidin * Prodelphinidin * |
aerial culm # |
[12] |
E. spathacea Mast. |
Syringetin 3-galactoside (12) |
stem, inflorescences |
[11] |
E. tectorum (L.f.) Moline and H.P.Linder |
Laricitrin 3-galactoside (9) Syringetin 3-galactoside (12) Procyanidin * Prodelphinidin * |
stem, inflorescences; aerial culm # |
Table 3. Chemical Structures of the 3-hydroxyflavone (flavonol) derivatives of Elegia species.
Chemical Name |
R1 |
R2 |
R3 |
Kaempferol (1) |
OH |
H |
H |
Quercetin (2) |
OH |
OH |
H |
Quercetin 3-galactoside (3) |
O-gal |
OH |
H |
Myricetin (4) |
OH |
OH |
OH |
Myricetin 3-galactoside (5) |
O-gal |
OH |
OH |
Myricetin 3-arabinoside (6) |
O-ara |
OH |
OH |
Myricetin 3-rhamnoside (7) |
O-rha |
OH |
OH |
Laricitrin (8) |
OH |
OMe |
OH |
Laricitrin 3-galactoside (9) |
O-gal |
OMe |
OH |
Laricitrin 3-rhamnoside (10) |
O-rha |
OMe |
OH |
Syringetin (11) |
OH |
OMe |
OMe |
Syringetin 3-galactoside (12) |
O-gal |
OMe |
OMe |
Syringetin 3-arabinoside (13) |
O-ara |
OMe |
OMe |
Syringetin 3-rhamnoside (14) |
O-rha |
OMe |
OMe |
The present review described thoroughly all the existing knowledge and research advances of the genus Elegia L. It focused on highlighting the importance of this genus as a major component of the fynbos biome, as well as its integral role in the cultural practices and everyday life of locals. Furthermore, taking also in consideration the recent results on the anti-wrinkle effects of E. tectorum, this overview unveiled the promising role of Elegia spp. as potential medicinal plants of South Africa with rich bioactive phytochemical content.
As a result, this study could be a stimulus for further research of the Elegia genus or even the entire Restionaceae family. In addition, it could be used as a guide for scientists in need of uncharted species that have not yet been fully explored. The fact that no Elegia species has been used traditionally as a medicinal plant should not be a prohibitive factor since scientists today have the necessary tools to unveil the hidden treasure of novel specialized metabolites of species that may have eluded human curiosity and history up until today. The research that has been conducted for the Elegia genus is very limited. Though, the results which are summarized herein clearly indicate that these plants could be a promising source and very beneficial for the local population and economy. Further studies should be carried out to acquire a better understanding on the phytochemistry and the pharmacological properties of the Elegia species.